1. Field of Invention
The invention relates to a carrier film and an integrated circuit device using the same and a method of making the same.
2. Description of Related Art
Integrated circuit devices (hereinafter referred to as BGA-T) using conventional carrier films, including the one shown in FIGS. 4 and 5, are known. FIG. 4 is a plan view of the BGA-T of the related art, and FIG. 5 is a cross-sectional view taken along line 101-102 of FIG. 4. A carrier film to be used in the BGA-T defines a device hole 2 in which an integrated circuit element 1 is disposed. Inner leads 4, to be connected to electrodes 3 of the integrated circuit element 1, extend into the device hole 2 in the form of cantilevers. Normally, a film 5 is formed from heat-resistant resin, such as polyimide resin. External electrodes (external terminals) 6 are disposed in a plane on one surface of the film 5. Solder balls or gold-plated copper bumps are used as the external electrodes 6. The inner leads 4, to be connected to the electrodes 3 of the integrated circuit element 1, extend on the film 5, defining wire leads 7 that are connected to the external electrodes 6. After the inner leads 4 of the integrated circuit element 1 are connected to the electrodes 6 of the carrier film, the integrated circuit element 1, the inner leads 4 within the device hole 2 and portions of the film 5 adjacent the device hole are coated with liquid sealing resin 8, and the liquid resin is heated and hardened.
The BGA-T finished in this manner is placed on an external substrate which is printed with solder paste at locations corresponding to the external electrodes 6, and then subjected to a reflow process so that it is mounted on the external substrate.
However, in the conventional structure shown in FIGS. 4 and 5, no film exists in a region of the device hole 2 where the integrated circuit element 1 is positioned, that is, there is a gap around the circuit device 1 to the edge of the device hole 2, the inner leads 4 connected to the electrodes 3 of the integrated circuit element 1 extend only from the film 5 that is located outside of the integrated circuit element 1. The inner leads 4 are connected to the external electrodes 6 through the wire leads 7. As a consequence, external electrodes cannot be disposed in a region corresponding to the device hole 2 where the integrated circuit element 1 is located.
In order to increase the mounting density, it is necessary to dispose as many external electrodes 6 as possible in an area that is taken by the package and connect them to an external substrate. However, when the conventional BGA-T is connected to an external substrate, the region corresponding to the device hole 2 is wasted.
Japanese laid-open patent application HEI 8-83818 describes that a carrier film is divided into a first region for disposing a semiconductor circuit device and a second region about the first region, and external electrodes are disposed on both of the regions. In the carrier film described in Japanese laid-open patent application HEI 8-83818, the external electrodes in the second region are disposed in a staggered manner. As a consequence, if the size of an integrated circuit differs, a socket and a substrate specifically acceptable to the arrangement of the external electrodes are required when the integrated circuit device is examined. It is troublesome to change and maintain these elements, and the work required for the examination process is complicated.